Radio frequency (RF) filters are often used in RF amplification devices to filter undesired signal components (e.g., harmonics and noise) from RF signals. For example, an RF amplification device may include a closed-loop control system that stabilizes the performance of the RF amplification device. An RF signal may be received as feedback and reference signals by the closed-loop control system in order to linearize the performance of the RF amplification device. An RF filter, such as a harmonic filter, may be used to filter harmonics from the RF signal in order to maintain the operation of the closed-loop control system. However, typical RF filters offer a hard tradeoff between harmonic rejection, bandwidth, and filter order. This constitutes a hard barrier for the use of closed-loop control circuits with RF amplification devices since the down-converted harmonics may result in linearization error, thereby causing distortion. Furthermore, reference and feedback paths in the closed-loop control circuits may suffer from degradation due to broadband noise. For instance, the broadband noise may be down-converted and folded on top of signals in the reference and feedback paths, resulting in degraded signal-to-noise ratios (SNRs). RF filters with weak mutually magnetically coupled inductor coils improve performance and have higher quality (Q) factors. Unfortunately, traditional weakly mutually magnetically coupled inductor coils consume large amounts of area, since the inductor coils must be placed a large distance apart (e.g., a distance several times greater than a diameter of the inductor coils) in order to obtain weak mutual magnetic coupling. Thus, more compact weakly magnetically coupled inductor structures are needed for RF filters.